压力载荷对声波测井圆管换能器影响有限元分析

Finite Element Analysis of Effects of Pressure Load on Acoustic Logging Tube Transducer

基于有限元方法数值分析压力载荷对声波测井圆管换能器的影响,研究不同压力条件下换能器频率响应、发射特性的变化。随着对换能器上下两底面施加压力的增加,换能器各振动模态谐振频率降低,当压力增大到一定数值某些振动模态消失,产生新的振动模态。随着压力的增加,在空气中换能器谐振频率逐渐降低,在21.82kHz谐振点处的电导值上升,在16.01kHz谐振点的电导值先升高后降低并逐渐消失,在14.64kHz谐振点处的电导值降低并逐渐消失;在流体中换能器谐振频率降低,对应的电导值均降低。随着压力的增加,换能器在流体中的发射电压响应值在高频段会上升,在低频段会先略有上升后下降。数值模拟结果可以对正确制作、装配圆管换能器起到良好的指导作用。

Analysed is pressure load effects on tube transducer of acoustic logging with the finite element method. Investigatived are the changes of frequency response and transmit response of transducer under different pressure conditions. The results show that transducer＇s resonant frequency of each vibration modal will reduce when the pressure on the transducer increases. Some vibration modal will disappear and new modal will show up. The resonant frequency of transducer which in the air will reduce when the pressure increases, the electric conductance on resonance point 21.82 kHz will increase. The electric conductance on resonance point 16.01 kHz will increase at first and then reduce and disappear at last. The electric conductance on resonance point 14. 64 kHz will reduce and disappear at last. The resonance point in low frequency will disappear while the pressure increases into some level. The resonant frequency of transducer which in the water will gradually reduce when the pressure on the surface of transducer increases and the electric conductance on resonance point will gradually reduce. Transducer＇s transmit response in fluid will increase a little and then reduce in low frequency and increase in high frequency when pressure increases. The results of numerical simulation are good guide for making and assembling transducer correctly.